Method of producing catgut threads and strings



June 14, 1960 H. KIRSCHBAUM METHOD OF PRODUCING CATGUT THREADS AND STRINGS I Filed June 16, 1958 J/VVE/VTOR.

United States Patent METHOD OF PRODUCING CATGUT THREADS AND STRINGS Hans Kirschbaum, Number-g, Germany, assignor to R. Graf & Co., Siiddeutsche Catgutfabrlk, Numberg, Germany Filed June 16, 1958, Ser. No. 742,320

Claims priority, application Germany July 15, 1953 12 Claims. (Cl. 57-160) The present invention relates to a new method of producing threads, strings, or cords from animal raw materials, to be used as surgical thread, for stringing musical instruments or tennis rackets, and various other purposes.

This application is a continuation-in-part of my copending application Serial No. 441,869, filed July 7, 1954, now abandoned for Catgut.

Heretofore, violin strings and catgut threads have been obtained solely by combining strips of intestines in wet condition, this being accomplished by twisting together a plurality of individual (and wet) strips into the form of a string or thread. The formation of this wet string or thread is followed immediately by the drying of the string or thread. The drying operation causes sticking or, technically expressed, adhesion of the wet intestine strips to form a homogeneous thread.

The present invention is based upon an entirely new concept. It proposes to combine the single intestine strips not by drying and attendent adhesion of the raw material, but rather by uniting extremely fine prefabricated threads as such, i.e., without any subsequent drying and adhering thereof in the form of dry threads by braiding, winding or spinning. The known drying procedure used in the manufacture of strings or catgut threads is only applied in the present invention for the preparation of the prefabricated threads.

According to the prior art methods, the drying of the surgical threads was invariably effected after the twisting thereof. This inherently produced a considerable reduction in the cross section of the finished product. Since the properties of the different intestinal sections used for the preparation of the strips always vary to some extent and can not be determined in advance, it is impossible with the prior art methods to manufacture threads or strings having a definite predetermined final cross section. However, in most cases, the user is only able to utilize strings or threads that possess very definite diameters. This cannot be accomplished with the prior art methods without waste. For example, if, in accordance with the prior art methods, it were desirable to produce a final catgut thread of No. 3 size (0.53 mm. diameter), it would be necessary to select a certain number of strips of raw materials having a combined Width in the wet state which would most likely yield, after drying, a resulting thread possessing a diameter of the order of 0.53 mm. However, at the same time, there would be produced a large number of threads of No. 4 size (0.61 mm. diameter), i.e., of a size that is seldom used. It follows that, as the need for No. 3 threads becomes greater, the stockpile of No. 4 threads will increase accordingly without the necessary outlet therefor. This, in turn, results in a higher cost for the product which .is in greater demand.

The above drawbacks are completely removed by the "ice threads. These thin prefabricated single threads have an accurately predetermined diameter. Due to the finenessof these threads, fluctuations in the thread diameter are confined to very narrow ranges. The prefabricated. threads are now twisted or braided into structures of predetermined diameters, whereby the desired diameter is arrived at in the simplest way, twisting together in the dry state a corresponding number of single threads having accurately known and unchangeable diameter. The conventional after-treatment of the final product by abrading and polishing, which was necessary to meet certain requirements of thread size and smoothness of the surgical catgut, can be dispensed with in the exercise of the present invention.

The threads prepared in accordance with this new method distinguish over the known products by their considerably increased flexibility, tensile strength and, above all, by their even and uniform diameter extending over the entire length of the thread. Moreover, due to the looser structure of the new catgut thread, the resorption thereof is enhanced in case of clinical use.

In contrast to the prior art methods, the present invention makes it possible to produce surgical threads of any suitable length by the application of an extremely simple mode of operation, without the occurrence of undesired thickening of the thread. This is accomplished by knotting together the prefabricated single threads before the twisting or braiding thereof into the final catgut product. The small knots at the connecting points are barely noticeable in the end product.

According to some of the prior art methods, it is proposed in the manufacture of endless threads to knot the wet intestine strips to each other. This is obviously made very difficult in view of the slipperiness and extensibility of the intestine strips. Moreover, undesirable thickening of the threads takes place at the knotting points. In order to avoid this drawback, it has already been suggested to fasten the intestine strips to one another by rolling, splicing and pressing. However, these operations are not only tedious and relatively expensive, but are also incapable of producing threads of predetermined diameter. This is now possible in accordance with the present invention by knotting together prefabricated threads of known thickness and by combining the endless threads thus prepared.

It is an important object of this invention to cut strips of very slight thickness, in the order of 0.005 mm., and of narrow width, in the order of about 6 mm., from sheep intestines or other animal substance, such as tendons, skins or the like. Since the thickness of the intestine, etc., is generally non-uniform, each narrow ribbon or strip of material cut therefrom is twisted about the longitudinal Y axis of the strip, so as to produce a single thread of uniform diameter, which thread will not be affected by the small differences in thickness of the intestine, etc., from which the strip was cut originally.

It is another object of the invention to devise a method of producing a catgut of any desired length and thickness with'a uniformity far superior to any similar product previously made.

Another object is a method of making such thread which is superior, especially for surgical purposes, because of its high degree of flexibility, its thinness, high tensile strength, and high absorptive qualities, and the facility of sterilizing the same.

The principal feature of the invention consists in making the catgut from fine prefabricated threads so as to form a rope or braid which may either be used in such a state or be coated by a covering of similar threads so as to reinforce their structure.

Further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and sco'peof the invention will become apparentto those skilled in the art from this detailed description.

In the drawings:

amass Figure .1 shows a narrow ribbon cut from animal in- Figure 4 shows a thinplaited rope orv cable with a core 7 7 formed by the thread as shown in Figure 3 Figure 5 shows a rope-like catgut .in which the outer covering is made similarly to that shown in Figure 4, but containing a core similar to that shown in Figure 2;

Figure 6 shows a catgut similar to that illustrated in.

Figure 5,,but with a differently braided covering;

Figure '7 shows still another form of making the outer covering;

Figure 8 illustrates the knotting or tying together of the individual-threads shownin Figure 2;

Referring in detail to the drawings, the strips or ribbons 1, shown in Figure 1, are cut from sheep intestines or'other animal substance, such as tendons, skins, or the I like. The sheep intestine, for example, is preconditioned in the conventionalmanner by soakingthe same in alkaline solution until the wet intestine weighs approximately three times as much as it would weigh in the dry condition. p

The strips or ribbons 1 are then cut fromthe wet intestinein an essentially conventional manner by means of 3 suitable slitting devices; however, these strips are cut so as' to be considerably narrower in width than'any similar strips heretofore employed for the purpose of the present invention; For example, an intestine having a diameter of 8 mm. and a circumference ofabout 25 mm. was'divided longitudinally into four parts, furnishing strips of about 6 mm. width. The thickness of thewall of the intestine was determined to be'about 0.0030.007-mm.,preferably. 0.005 mm. when the intestine was in the dried thread, such as a thread}, around the core state; thus the wet strips would be about'3 to.9 mm.,

' preferably 6 mm. in width and slightly greater than 0.005 mm. in thickness.

Each of the individual strips 1, after having been cut andwhile still moist, is-twisted about a longitudinal axis 7 (on itself), so as to produce a resulting thread 2 of uniform diameter, as shown in Figure 2. The threads of Figure 2 are dried (in the twisted state) and may then be used to produce the various forms illustrated in Fig. ures 3 to 7. Depending upon the lengths of the stripsz, formed as indicated above, it may be-desirable to tie two or more threads together, so as to form a longer continuous th'readgth'erefore, after being assorted, the threads are joined together by forming'small knots '12, as shown-in Figure 8. The thin threads may be wound in any suitable length upon spools or bobbins and may b' jplaced in suit- I able machines of the type known for making-textiles:

As indicated above, the conventional threads and strings, know'n as catgut,"are manufactured by cutting individual strips, twisting a plurality-of strips together degreeof accuracy. Thus if it were .desired to. produce a diameter Such reductioninmaterial,obviously, also requantity of size 3 threads in accordance withfthe prior art methods, a large'proportion of size 4 threads would be produced at the same-time; Of .course,-.if therelw'erel no similar demand for size 4 threads, then the process would be wasteful or, at best, ver ineificient.

The present invention, on the other hand, involves the formation of individual smaller threads of uniform diameter which are combined to form the catgut only after the individual threads have been :dried. Thus, after drying, the threads ShQWIL'lIIl' Figurel having a possible size range of 0.004 to 0.009 inch in- .dianieter, may be very accurately assorted as to size, if necessary; then, since ing 5, fashioned from dried strips 1 or dried threads 2,

around a core 4, similar to the combined. threads 3 of Figure 3.

Figure 5 shows a modification wherein the core 6 is the same as the single thread 2 of Figure.2 and wherein the covering .7 is substantially thesame as the coverings of Figure 4. e a

Figure 6 shOWs a modification similar to that of Figure 5, wherein the inner core 8 is a single strand of thread, such as shown in Figure. 2, and wherein the outer. covering 9 is woven from threads, such as shown in Figure 2.

Figure 7 shows a modificationsimilar to that of Figure 5, whereinthe inner core 1 0 is asingle strand of thread, such as is shown in Figure 2, and wherein theouter covering 11 is formed merelyby spinning or twistinga single The threads, strings, or; cords made according to the invention have the following, advantages .over the ca tgut previouslymade: p

. The catgut of any type madeaccording to prior methods, either in the form. of threads, strings, or cords, was

,so stiff and inelastic that, for surgical purposes, itfir'sjt had to be treated witha softening agent, for example, a watery alcohol or alcohol to which a special softener, was

added. Such. softening agent, however, loosens the 46 thread structure and, thereby, reduces the tensilestrength of the catgut. The. thread, string, or cord, made according to. the invention, on the other hand, is so flexible that it can .be used directly, i.e.,.without any pretreatment by a softening agent.

so as to protect it from drying. out, aliphatic. or aromatic Therefore, for storing it, in a manner hydrocarbons may beused rather than alcoholic or other softeningagents.

The tensile strength of the threads, strings, or cords,

55' according to the invention is considerably higher than that of the ca-tgut as previously made, for the reason that, inthe present case, it includes the sum total of the tensile strength. of the individual threads which are woven,

' braided'or. spun together. Furthermore, it is a fact well threads,.strings,-or cords made according to the invention, 7 may be used for the same purposes as theprior products without, however, being required. tobe of such thick duces-the cost of thefinal product, a fact which is ofimportance-particularly when .the..catgut is to beused for tennis-rackets, musical instrumentsfand ,other technical Pu poses. V V I V The sterilization of the former. products for surgical purposes also entailed 'variouspthei difiiculties. The iinew product, however, because, of its structure ofindividual .fine threads, allows the chemical, sterilizing agents, to

7 s entenitheiinside; ther'eohvery easily 'and%guickly and, thus,

insures the sterilization to be completely successful in every case.

Finally, due to their greater tensile strength and flexibility, the threads according to the invention, when sed for surgical purposes, insure a firmer and more reliable hold of the knots oi ligatures and sutures than tl ose made with previous products, in spite of the fact that the individual threads are thinner. Also, the new structure of individual line threads with thinner diameter, facilitates the penetration of the cat ut by the blood corpuscles, causing the threads, after accomplishing their purpose, to disintegrate and to be easily absorbed by the body.

I claim:

1. A nethod of producing catgut threads and strings comprising the steps of first cutting moist narrow ribbons of to 0.007 thicl ess, 3 to 9 mm. Width, of a moistened raw animal intestine, twisting said moist ribbons and drying said twisted moist ribbons thereafter so as to form thin threads, and combining several threads so as to reinforce each other.

2. A method according to claim l, wherein said ribbons have a thickness of 0.005 mm.

3. A method according to claim 1, wherein said ribbons have a width of 6 mm.

4. A method of producing catgut threads and strings comprising the steps or" first cutting moist narrow ribbons of a raw animal intestine, said intestine being preconditioned by soaking the same in alkaline solution, twisting said moist ribbons and drying said twisted moist ribbons thereafter so as to form thin threads, and twisting together several threads so as to reinforce each other.

5. A method of producing catgut threads and strings comprising the steps of first cu ing moist narrow ribbons of a raw animal intestine, sad intestine being preconditioned by soaking the same in alkaline solution, twisting said moist ribbons and drying said twisted moist ribbons thereafter so as to form thin threads, and braiding together several threads so as to reinforce each other.

6. A method of producing catgut threads and strings comprising the steps of first cutting moist narrow ribbons of about 0.005 mm. thickness, and about 6 mm. width, of a moistened raw animal intestine, twisting said moist ribhens and drying said twisted moist ribbons thereafter so as to form thin threads, tying together a plurality of said threads to extend their length, and combining several such threads so as to reinforce the same.

7. A method of producing catgut threads and strings comprising the steps of first cutting moist narrow ribbons of a raw animal intestine, said intestine being preconditioned by soaking the same in alkaline solution, twisting said moist ribbons and drying said twisted moist ribbons thereafter so as to form thin threads, tying together a plurality of said threads to extend their length, and coating said threads with a covering of additional threads of the same material.

8. A method of producing catgut threads and strings comprising the steps of first cutting moist narrow ribbons of about 0.005 mm. thickness, and about 6 mm. width, of a moistened raw animal intestine, twisting said moist ribbons and drying said twisted moist ribbons thereafter so as to form thin threads, tying together a plurality of said threads to extend their length and spinning an additional fine thread of the same material around said first threads so as to reinforce the same.

9. A method of producing catgut threads and strings comprising the steps of first cutting moist narrow ribbons of about 0.005 mm. thickness, and about 6 mm. width, of a moistened raw animal intestine, twisting said moist ribbons and drying said twisted moist ribbons thereafter so as to form thin threads, tying together a plurality of said threads to extend their length and braiding several fine threads of the same material around said first threads so as to reinforce the same.

10. A method of producing catgut strings which comprises the steps of cutting moist narrow ribbons of about 0.005 mm. thickness, and about 6 mm. width, of a moistened raw animal intestine, twisting each of said moist ribbons upon itself, drying each of the so twisted moist ribbons to form individual thin threads, and combiriing several of said threads to produce a resulting catgut string.

11. A method of producing catgut strings which comprises the steps or" cutting moist narrow ribbons of about 0.005 mm. thickness, and about 6 mm. width, of a moistened raw animal intestine, twisting each or" said moi ribbons upon itself, drying each of the so twisted moist ribbons to form individual thin threads and twisting together a plurality of said threads so as to produce a resulting catgut string.

12. A method of producing catgut strings which comprises the steps of cutting moist narrow ribbons of about 0.005 mm. thickness, and about 6 mm. width, of a moistened raw animal intestine, twisting each of said moist ribbons upon itself, drying each of the so twisted moist ribbons to form individual thin threads and braiding together a plurality of said threads so as to produce a resulting catgut string.

References Cited in the file of this patent UNITED STATES PATENTS 1,281,466 Wise et a1. Oct. 15, 1918 2,649,833 Crandall Aug. 25, 1953 FOREIGN PATENTS 310,884 Great Britain Feb. 20, 1930 

